Indirect evidence of deep flow east of a North Pacific seamount     

Kern E. Kenyon 《Journal of Oceanography》1978,34(6):288-294

East-west vertical sections centered on Kinmei Seamount (35N, 172E) of potential temperature, salinity, and oxygen, based on recent standard hydrographic measurements, and vertical profiles ofin situ temperature and density ( ₄) east of the seamount, based on STD data, show contrasting variability in the deep water characteristics east and west of the seamount. These data are consistent with horizontal variations in water mass properties (temperature-salinity and temperature-oxygen curves) east of the seamount between 2,600–3,900 m but not west of the seamount. East of the seamount on surfaces of constant potential temperature (or density) salinity and oxygen are higher at a station 200 km from the seamount than at stations on either side. From these relations and from known deep water properties of the North Pacific, it is suggested that east of the seamount, between 2,600–3,900 m, the observations are consistent with northward flow, which is interpreted to be a western boundary current with an east-west scale of about 300 km.  相似文献   

Non-biological fractionation of stable Ca isotopes in soils of the Atacama Desert, Chile     

Stephanie A. Ewing  Wenbo Yang  Greg Michalski  Brian W. Stewart  Ronald Amundson 《Geochimica et cosmochimica acta》2008,72(4):1096-1110

We measured Ca stable isotope ratios (δ^44/40Ca) in an ancient (2 My), hyperarid soil where the primary source of mobile Ca is atmospheric deposition. Most of the Ca in the upper meter of this soil (3.5 kmol m⁻²) is present as sulfates (2.5 kmol m⁻²), and to a lesser extent carbonates (0.4 kmol m⁻²). In aqueous extracts of variably hydrated calcium sulfate minerals, δ^44/40Ca_E values (vs. bulk Earth) increase with depth (1.4 m) from a minimum of −1.91‰ to a maximum of +0.59‰. The trend in carbonate-δ^44/40Ca in the top six horizons resembles that of sulfate-δ^44/40Ca, but with values 0.1-0.6‰ higher. The range of observed Ca isotope values in this soil is about half that of δ^44/40Ca values observed on Earth. Linear correlation among δ^44/40Ca, δ³⁴S and δ¹⁸O values indicates either (a) a simultaneous change in atmospheric input values for all three elements over time, or (b) isotopic fractionation of all three elements during downward transport. We present evidence that the latter is the primary cause of the isotopic variation that we observe. Sulfate-δ³⁴S values are positively correlated with sulfate-δ¹⁸O values (R² = 0.78) and negatively correlated with sulfate δ^44/40Ca_E values (R² = 0.70). If constant fractionation and conservation of mass with downward transport are assumed, these relationships indicate a δ^44/40Ca fractionation factor of −0.4‰ in CaSO₄. The overall depth trend in Ca isotopes is reproduced by a model of isotopic fractionation during downward Ca transport that considers small and infrequent but regularly recurring rainfall events. Near surface low Ca isotope values are reproduced by a Rayleigh model derived from measured Ca concentrations and the Ca fractionation factor predicted by the relationship with S isotopes. This indicates that the primary mechanism of stable isotope fractionation in CaSO₄ is incremental and effectively irreversible removal of an isotopically enriched dissolved phase by downward transport during small rainfall events.  相似文献   

Earthquakes and strength in the laminated lower crust —Can they be explained by the “corset model”?     

Rolf Meissner  Hartmut Kern 《Tectonophysics》2008,448(1-4):49-59

We present a model that may explain deep crustal earthquakes observed, in particular, in several areas of highly reflective (laminated) lower continental crust. We combine observations from earthquake seismology, crustal reflection seismics and tectonic-rheological concepts. The study concentrates on parts of the northern Alpine foreland where many earthquakes occur inside the laminated lower crust, which is generally considered to be warm and weak. Thin mafic/ultramafic, sill-like intrusions and invisible dykes are assumed to form a corset-like network with high strength. This model can explain the observed strong and multiple reflections and the occurrence of rupture inside a stable structure within a weak lower crust. Tectonic stress transfer (from the Alpine collision zone or/and the Upper Rhine Graben) and its release may follow classical friction concepts. In addition, the heterogeneity of the laminated lower crust may also favour various viscous instabilities.  相似文献   

Polynya Area in the Kara Sea, Arctic, Obtained With Microwave Radiometry for 1979–2003     

Kern  S. 《Geoscience and Remote Sensing Letters, IEEE》2008,5(2):171-175

The polynya signature simulation method is applied to satellite microwave radiometry data to get the mean (January-April) polynya distribution in the Kara Sea for 1995-2004. Temporal variability of polynya location and extent is confirmed with the variability of ERA40 surface wind speeds. The mean (January-April) fraction of ice area of 65%-85% ice concentration relative to the mean daily total Kara Sea ice area agrees well (correlation coefficient: 0.79) with the mean daily total Kara Sea polynya area for 1996-2003. The resulting linear fit is used to extend the polynya area time series until 1979. During 1979-2003, the polynya area increased by 2400 km²/dec. This is accompanied with slightly increasing southerly winds. Polynyas in the eastern Kara Sea seem to play a nonnegligible role for the winter-time Kara Sea ice export.  相似文献   

Phase composition and radiation stability of matrices for isolation of REE-actinide waste     

Laverov  N. P.  Yudintsev  S. V.  Stefanovsky  S. V.  Ewing  R. Ch. 《Doklady Earth Sciences》2012,443(2):526-531

Doklady Earth Sciences -  相似文献   

Procedures,Resources and Selected Results of the Deep Ecliptic Survey     

Buie  M. W.  Millis  R. L.  Wasserman  L. H.  Elliot  J. L.  Kern  S. D.  Clancy  K. B.  Chiang  E. I.  Jordan  A. B.  Meech  K. J.  Wagner  R. M.  Trilling  D. E. 《Earth, Moon, and Planets》2003,92(1-4):113-124

The Deep Ecliptic Survey is a project whose goal is to survey a largearea of the near-ecliptic region to a faint limiting magnitude (R ～24) in search of objects in the outer solar system. We are collectinga large homogeneous data sample from the Kitt Peak Mayall 4-m and CerroTololo Blanco 4-m telescopes with the Mosaic prime-focus CCD cameras.Our goal is to collect a sample of 500 objects with good orbits to furtherour understanding of the dynamical structure of the outer solar system.This survey has been in progress since 1998 and is responsible for 272designated discoveries as of March 2003. We summarize our techniques,highlight recent results, and describe publically available resources.  相似文献   

Physical Characterization of the Binary Edgeworth–Kuiper Belt Object 2001 QT 297     

Osip  David J.  Kern  S. D.  Elliot  J. L. 《Earth, Moon, and Planets》2003,92(1-4):409-421

Following our discovery of 2001 QT₂₉₇ as the second knownbinary Edgeworth–Kuiper Belt Object (EKBO) in October of 2001 [IAUC 7733], we havecarried out additional high spatial resolution ground based imaging in October andNovember of 2001 and July, August, and September of 2002. Using the Raymond andBeverly Sackler Magellan Instant Camera (MagIC) on the Baade and Clay 6.5 m telescopesat Las Campanas Observatory in Chile, we have obtained accurate astrometric and photometricmeasurements in the Sloan r’ i’ and g’ filters. Superb seeing conditions andPSF fitting allow an accurate determination of the binary component separation and positionangle over time as well as a detailed study of color and temporal variability of the individualcomponents. Here we present a physical characterization of the individual componentsof 2001 QT₂₉₇ based on these astrometric, color and variability measurements. We findthe primary to exhibit colors about 0.3 magnitudes redder than solar with no evidencefor variability. The secondary component, however, exhibits strong variability(～0.6 magnitudes) with a best fit period of 4.7526 ± 0.0007 h for a single peaklightcurve or 9.505 ± 0.001 h for a dual peaked lightcurve. The colors measured for thesecondary also suggest variability. Based on a preliminary orbit fit for thepair using observations spanning a one year arc, we are able to estimate a system mass of～ 3.2 × 10¹⁸ kg and provide constraints to the surface albedo of 9–14% for assumeddensities between 1 and 2 g/cm³.  相似文献   

Discovery and characteristics of the Kuiper belt binary 2003QY90     

S.D. Kern  J.L. Elliot 《Icarus》2006,183(1):179-185

We present photometric and astrometric results from four epochs of ground-based observations at the Magellan telescopes of the Kuiper belt binary 2003QY90. Resolved observations show both components to be highly variable and often of nearly equal brightness, causing difficulty in distinguishing between the primary and secondary components for observations spaced widely in time. Resolved lightcurve observations on one night show one component to have a single-peaked rotation period of 3.4±1.1 h and a peak-to-peak amplitude of 0.34±0.12 mag. The other component exhibits a less constrained lightcurve, with a single-peaked rotation period of 7.1±2.9 h and a peak-to-peak amplitude of 0.90±0.36 mag. Under the assumption of equal albedos, the diameter ratio is 1.25±0.11 in the Sloan i^′ filter. While we cannot determine an orbit from our four distinct epochs of observation (due to ambiguity in component identification), we place limits on the orbital period of the system of 300-600 days, we find a minimum semi-major axis of 13,092 km for a circular orbit and a system mass range of (2.3-18.0)×¹⁰¹⁷ kg depending on the identification of components in our observations.  相似文献   

Reply to comments by T. Oberthür on “Trace element distribution in uraninite from Mesoarchaean Witwatersrand conglomerates (South Africa) supports placer model and magmatogenic source”     

H. E. Frimmel  M. Depiné  P. Emsbo  A. E. Koenig  M. Kern 《Mineralium Deposita》2013,48(8):1051-1053

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Cometary charge exchange diagnostics in UV and X‐ray     

D. Bodewits  D.J. Christian  J.A. Carter  K. Dennerl  I. Ewing  R. Hoekstra  S.T. Lepri  C.M. Lisse  S.J. Wolk 《Astronomische Nachrichten》2012,333(4):335-340

Since the initial discovery of cometary charge exchange emission, more than 20 comets have been observed with a variety of X‐ray and UV observatories. This observational sample offers a broad variety of comets, solar wind environments and observational conditions. It clearly demonstrates that solar wind charge exchange emission provides a wealth of diagnostics, which are visible as spatial, temporal, and spectral emission features. We review the possibilities and limitations of each of those in this contribution (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献